It is common practice to screen targets, including people, freight, luggage and other items, to detect the presence of illicit substances. Illicit substances include, for example, weapons, narcotics, explosives, chemical warfare agents, biological warfare agents, nuclear or radiological agents, ammunitions, toxic industrial chemicals or waste, and controlled or contraband items such as tobacco.
This screening is often conducted in locations where security or safety is a principal concern, such as at a border crossing between countries, or in an airport or another transportation hub. It may be done to guard against terrorism, prevent the movement of weapons or drugs, or to control trade.
Traces of illicit substances may be present on people who carry, handle or otherwise come into contact with illicit substances. For example, concealed explosives or other illicit substances under garments may emit vapors, which may be detected through clothes or other packaging. The processing of concealing the illicit substances may have left microscopic traces of the illicit substance on a person, or on the surfaces that have come into contact with the illicit substance. Detection of these substances requires costly and bulky equipment which may require specialized training to operate, which has discouraged their wide-spread use.
Illicit substances that contain radioactive particles may be detected using a variety of technologies, such as sodium iodide detectors, or technologies exploiting a Geiger-Mueller tube, each of which is a stand-alone device.
To detect these substances on a person or on luggage or other items, a person may be physically examined (i.e. patted down) for unusual items, and items may be swabbed and the samples analyzed for traces of illicit materials. Dogs are sometimes used to detect illicit materials, but must be specially trained to do so, at considerable time and expense. To detect weapons, metal detectors using magnetic fields are typically employed on people, and x-ray technologies on items that can tolerate the radiation.
These methods are time consuming and costly. It may take many minutes to perform these steps to a person and their luggage in a typical scenario, such as in an airport, using separate devices and separate personnel. A busy airport may move many thousands of individuals, and their luggage, a day through its gates, and performing all of these steps separately in such an airport would be an enormous and costly undertaking using current technologies. There is a need for a system that screens for all of these threatening target substances simultaneously.